Method of forming tubular members having thick walled end portions



April 9, 1940. H. D.'HEMAN\ METHOD OF FORKING TUBULAR MEMBERS HAVINGTHICK WALLED END PORTIONS 3 Sheets-Sheet 1 Filed Dec. 30, 193'? HOMER D.HEMAN ATTORNEY.

H. D. HEMAN 2,196,497

METHOD OF FORIING TUBULAR MEMBERS HAVING THICK WALLED END PORTIONS An'ls, 1940.

Filed Dec. 50, 1937 3 Sheets-Sheet 2 INVENTOR HOMER D. HEMAN a ATTORNEY.

April 9, 1940. HEMAN 2,196,497

METHOD OF FORIING TUBULAR MEMBERS HAVING THICK WALLED END PORTIONS FiledDec. 30, 1937 :s Sheets-Sheet s 3o 29 INVENTOR. fiQJ? fi 15 HOMER D.HEMAN I @ATTQRNEY.

Patented Apr. 9,1940

UNITED STATES PATENT OFFICE METHOD OF FORMING TUBULAR MEMBERS HAVINGTHICK WALLED END PORTIONS Homer D. Heman, East Cleveland, Ohio, assignorto The Ajax Manufacturing Company, Euclid Village, Ohio, a corporationof Ohio Application December 30, 1937, Serial No. 182,557

3 Claims.

This invention relates to an improved method of producing a tubularmetal member having portions of varying wall thickness and particularlyend portions and end flanges of greater wall thickness than the normalwall thickness of the portion of the tubular member between the endportions and to a method of preparing a steel blank by roll forging forproducing such tubular metal members.

For the purposes of illustration, the present invention is describedherein in connection with the manufacture of torque tubes forautomobiles, its application to other metal tubularmembers being readilyapparent from the exemplary description and drawing.

Heretofore, tubular members of this general character, and particularlytorque tubes for automobiles, have been formed by any one of threegenerally practiced methods. The first method consists of providingthick wall flanged sleeves which either are cast or separately forged.These sleeves, in turn, are telescopically fitted over the end portionsof a length of tubing of uniform wall thickness and then spot welded orriveted to the length of tubing so as to provide a substantially unitarystructure. This method has been more or less superseded by butt weldingpreforged heavy-wall flanged sleeves to the ends of a length of tubingof uniform 'wall thickness or with an end slightly reduced in diameterand the end wall portion slightly thickened by swaging. The advantagesof a torque tube having its end portions thickened and formed intointegral flanges are such, however, that the practice he cameestablished of upsetting the ends of the tube to provide the additionalwall thickness desired and then forming one of the extreme end portionsof the tube into an annular or butt flange, and the other end portion ofthe tube either into a similar flange or bell, depending upon theparticular requirements of the torque tube.

This forging method, however, has proven expensive. For example, informing the flanged butt and of the torque tube or the bell end, it isnecessary to heat the end of the tube and, while the end is hot, toplace it in a suitable multiple impression forging die in an upsettingforging machine and therein to subject it successively to severalupsetting operations; After the second, third, or fourth step, dependingon the thickness of the tube wall and the speed at which heat isdissipated, it is necessary to reheat the tube and subject it to severaladditional successive operations in a different multiple impressionforging die, the last step of which finally forms the end portion of thetube to the desired form and thickness and, if desired, with the properflange. r

The number of upsetting or forming steps required is determined by theratio between the cross sectional area of the tube and the volume of theenlargements, but the operations must be gradual to avoid the folding orwrinkling ofthe tubular walls which would result in subsequent injuriousdefects, such as so-called cold shuts, in the reinforced or thickenedsections of tube. Sometimes the total number of operations canbe'accommodated in one pair of multiple dies of one forging machine buteven so the necessity of reheating to avoid working the stock too coldcalls for double handling at the furnace and forging machine. Morefrequently the number of operations required when upsetting portions ofstock tubing into heavily reinforced ends and flanges is such that allthe operations cannot be performed in the dies of one forging machineand a second machine, with a second furnace, must be provided, all ofwhich adds greatly to the labor of handling, expense of the operation,

and cost of equipment. Thus these operations necessarily requireconsiderable machinery and labor, and, more important, requireconsiderable time and handling of the member being forged, due to thereheating operation.

One of the-principal objects of the present in-, vention is to providean improved method of producing a metal tubular member with integralthickened and reinforced Wall portions of this character and whichrequires fewer upset forging operations with the consequent reduction oftime and handling of the material than the methods heretofore employedand as a result of which rejections because of defects or cold shutsdeveloped during the process and consequent ruin Another object is toprovide a method by which such tubular members may be formed more con- 7blanks or strip stock so as to provide blanks having thickened end orends, or intermediate portions, then forming said blanks into tubularform, welding the longitudinal edges of the same so as to provide atubular member having certain wall portions initially thickened inadvance of the die forging or upsetting operations, and then finallyheating the thickened portions and subjecting them to successivecombined upsetting and forging operations suficient to complete thedesired formation of said portions without additional reheating.

Another specific object is to roll forge a blank of flat metal of suchshape and proportions that it can be sheared into strips which, whenformed into tubular form, produce tapered tubular blanks with initiallythickened wall portions.

Another object is to design the shape of the blanks for forming tubularmembers which are to be tapered toward one end in such a manner that theblanks are in edgewise nested relation to each other and may be shearedfrom fiat band stock without waste of material, labor or time.

Other objects and advantages will become apparent from the followingspecification, wherein reference is made to the drawings, in which:

Fig. 1 is a plan view of one form of .blank to be operated on inaccordance with the present in vention for forming a tubular member ortorque tube of substantially uniform diameter throughout the majorportion of its length and slightly tapered inwardly toward one end;

Fig. 2 is a side edge view of the blank illustrated in Fig. 1;

Fig. 3 is a plan view of the blank after. it has been subjected to thefirst step of the present method;

Fig. 4 is a side view of the blank illustrated in Fig. 3; i

Fig. 5 .is a longitudinal sectional view of a partially formed torquetube which has been l t t d Fi 5 us m e m g and showing the final formthe intermediate portion being merged with the thereof;

Fig. 7 is anenlarged fragmentary sectional view through the completedbell end portion of the tube taken on a plane indicated by the line l-'lof Fig. 8, exemplary successive configurations of the end portion of thetubular member resulting in the bell portion being indicated in dottedlines and dot-and-dash lines, respectively;

.Fig. 8 is a cross sectional view taken on a plane indicated by the line8--8 in Fig. 7;

Fig. 9 is a sectional view of the thickened end portion of the tubemember taken on a plane indicated by the, line 9--9 in Fig. 7;

Fig. 10 is an enlarged fragmentary longitudinal sectional view throughthe flanged or butt end of the tube illustrated in Fig. 6;

Fig. 11 is an end elevation of the tube portion illustrated in Fig. 10;

Fig. 12 is a plan view of a strip of metal illustrating the manner inwhich nested blanks for a tapered tube may be cut from the metal'withoutwasting the material;

Fig. 13 is a side elevation of the band of stock with the formation of atorque tube for automobiles, their application to other tubular membersbeing readily apparent from the exemplary description and drawings.

The torque tube shown by way of illustration of the present invention isone which is tapered near one end and is to be provided with a bellportion at the tapered end portion and with a radial flange at theopposite or butt end. For this purpose, a length of the desired rolledstrip metal is cut off for forming a blank such as illustrated at I, thestock material used being of proper width so that lateral trimming tosize' is unnecessary preparatory to the first step of the method.

The blank I is then heated and passed between the rolls of a rollforging machine, one roll of which may be of constant diameter and theother roll of which may be either a. segmental roll or a complete rollhaving a reduced diameter portion. In passing the blank i between therolls, the rolls are so positioned initially that the extreme leadingend portion 2 of the blank is either not reduced in thickness or' isreduced in thickness a less amount than the remainder. The rollslikewise are such that at the opposite or trailing end portion 3 of theblank I, the extreme end is not reduced in thickness at all or is notreduced as much as the longitudinal midportion of the blank.

For the particular tube illustratively shown herein, the rollingoperation forms the blank such that substantially the entire leading endportion 2 and trailing end portion 3 are of their original thickness,while the intermediate portion t of the blank is of a reduced thickness,

portions 2 and 3 by sloping portions 5 and B, respectively, which are ofgradually'reduced thickness. The intermediate portion 6 of the blank l,between the portions 5 and 5, is reduced in thickness to the gaugedesired for the corresponding intermediate portion of the finished tube.

manner, the blank elongates materially at the portion i so that theoriginal blank may be cut to a length considerably less than the lengthof the finished tube to be formed therefrom. Further, during thisoperation, the blank widens slightly and the lateral edges are slightlyirregular, as indicated in Fig. 3. Since the blank is to be formed intoa welded tube, accurate edge surfaces are required to form the seamcleft. Consequently the marginal portions of the rolled blank aresheared oif, thus providing the correct width of the blank and at thesame time providing accurate edges for the subsequent Welding operation.Only suflicient material need be removed at the margins of the blank toprovide the correct width and shape of finished blank.

In the form illustrated, the tube is to be tapered at the bell end, thatis, at the end portion 2; and consequently more metal is trimmed ofi ofthe lateral margins of the blank at the end portion 2. The trim or shearline of the During the roll-forging of the blank I in this blank forforming the particular tube illustrated, is indicated at I in Fig. 3. Byshearing after roll-forging, not only is the blank brought accurately toshape but also the raw edge surfaces to be welded are clean cut and inmost desirable condition for the welding operation.

The blank I, after the roll-forging operations,

, blank defining the seam cleft, as indicated at I0.

In this condition, the seam is welded, preferably by stitch welding orother well known methe ods.

In the form illustrated, the blank has been rolled or pressed intotubular form with its under surface in the position shown in Fig. 4forming the outer surface of the tube, thus causing the thickenedmaterial to be disposed inwardly toward the axis of the tube in whichposition it may be more easily upset without danger of folding.' In someinstances, as will later be pointed out, the reinforcement or relativelyincreased thickness can be disposed to the outside of the tubing orpartly to the inside and partly to the outside.

Assuming the bell flange end is first to be formed, the left end of thetubular blank illustrated in Fig. 5 is heated and without reheating, issubjected to successive impressions of a multiple impression forgingmachine die, exemplary operations performed by the successive stages ofthe machine being illustrated in Fig. 7. In the first impression the endportion 2 is additionally upset and thickened while remaining tubular inform, as illustrated by dotted lines l2 in Fig. 7.

In the next impression, the end portion 2 is partially flared, asindicated by the dot-and-dash line I3 in Fig. 7. In the third or finalimpression of the machine, the portion 2 is given its final bell form,as indicated at H in Fig. '7. If extreme thickness of the bell portionis not necessary, the end portion 2 may be formed to the shape indicatedat IS in Fig. '7 in the first impression of a two-stage forging machine,the second impression of which machine imparts the final form, indicatedat H. Thus both the bellflanged portion of the tube and the contiguouspart of the portion 2 are of greater wall thickness than the wallthickness of the intermediate portion 4.

Referring next to Figs. 10 and 11, the successive steps of forming theradial flange or butt end of the torque tube are illustrated. After theformation of the bell end the butt end of the tube is heated. to arequired degree and subjected to successive combined upsetting andforging operations of a multiple impression die forging machine, thefirst of which impressions additionally upsets and forges the thickenedportion 3 to the shape indicated by the dotted line I! in Fig. 10, thesecond impression of which additionally upsets and forges the end to theshape indicated by the dot-dash line it in Fig. 10'and the thirdimpression of which forms a portion of the end of the tube into thefinal form with a thickened wall portion and a radial flange i'l. Duringeach of these successive combined upsetting and forging operations, thewall thickness or the tube at the portion 3 may be slightly increased atthe outer end.

The relative thickening of the end portions of the blank results in avery pronounced saving in time and an increase in the uniformity andhigh quality of the product over prior known methods. In this connectionit should be noted that the thickening of the wall by upsetting in suchforging operation is, as to each forging impression, about 50% of thewall thickness existing at the beginning of that particular operation.If the thickened end portions are formed from tubular stock havingoriginal thickness of the portion 4 of the blank, it is apparent thatthe increase in thickness which could be obtained in each forgingoperation would be materially reduced,- and if an' attempt were made toincrease the wall thickness more than about 50% of that existing at. thebeginning of the particular op- .eration the metal would fold andoverlap; By

starting with the increased wall thickness in the first instance at theportions 2 and 3, not only are the several forging impressions whichwould be'required to obtain this thickness eliminated but also theincrease of thickness for the steps actually used is much greater perstep. This effects a further reduction in the time and number ofoperations required to obtain the final thickness desired. This, ofcourse, is due to the fact that, in the fizrst forging operation, theamount of thickening is 50% of the original thickness of the metal stripat the portion 3 instead of 50% of the reduced thickness of the portion4 of the blank.

In the preferred embodiment of my method heretofore described, theblanks were formed preferably from strip stock of substantially thewidth desired in the finished blank, thus saving the cutting operationswhich would be necessary to out such blanks from a wider band ofmaterial.- The advantages of this, however, areoilset in some instancesby the loss of material in trim at the end portion 2. In many instances,it is desirable to form torque tubes which are tapered for substantiallytheir full length and in such instances the cutting of the blankstherefor from suchstrip stock would result in a considerable waste ofmaterial.

For tapered tubes, therefore, it is desirable to lay out the blanks innested condition as illustrated in Figs. 12 and 13, wherein a band ofstrip steel 20 of a width conforming to the length of the blank desired,allowance being made for elongation during rolling, is cut into blanks2i tapered from end to end of the blanks, that is, laterally of theoriginal strip stock, as indicated at 22. The blanks are nested with thelarge end of each blank being arranged between the smaller ends ofadjacent blanks. Thus, in the blanking operation, no metal is wasted.

The resultant blanks 2| are then roll-forged in the manner heretoforedescribed so as to provide the thickened end portions 23 and 24,respectively, with the intermediate portions 25 reduced in thicknessrelative to the original stock. After the roll-forging operation of suchblanks, the marginal portions 26 are trimmed off at the portion of theblanks of reduced thickness along the lines indicated at 21, At the sametime, the marginal portions of the unreduced end portions 23 and 24 aretrimmed off along the lines 28 so as to provide accurate and clean-cutedges for welding and at the same time to render the lateral edges ofeach end portion parallel to each other.

The blank is then formedinto the tube and forged at the ends asheretofore described. The, resultant tube, indicated at it in fig. in,is tapered and provided at its ends with flanged portions,

as indicated at St and 35, respectively, these portions being formed inthe same manner as the bell flange and butt flange portions or thetorque tube heretofore described.

As heretofore explained, the invention ha been described particularly inconnection with the forming of torque tubes for automobiles, wherein allof the advantages of the method are fully developed and utilized. Insuch tubes, it

is advantageous that the reinforcement or relative thickening of thewalls be disposed to the interior of the tube and the thick orreinforced portions of the tube occur only at one or both ends, theintermediate portion of the ,tubebeing of less thickness.

There are instances, however, in which it is desirable to provide tubeswith reinforcement at some other portion than at the ends and todisinforcement may be effected by the'steps of rollforging the blank toprovide relatively thickened wall portions so that when the blank isformed and welded into tubular form, certain desired portions arealready initially thicker than others. In such instances, it is oftenpossible to eliminate the additional upsetting forging steps, assufficient reinforcement can be provided. in the roll forgingoperations. When such tubes are comparatively long, the blanks thereforare passed through completely cylindrical forging rolls so arranged thatthe gap between the rolls can be increased readily when desired, thusproviding the relatively greater thickness by sop:

arating the rolls to the desired degree as the proper portions of theblank pass therebetween.

When the reinforcement is to be disposed partially on the inside andpartially on the outside of the tube, it may be provided for byundercutting both roll forging dies at the zone where the additionalthickness is required. Again, it is sometimes desirable to providethickened portions, such as reinforcing bosses, atelifierent areas ofthe tube, both on the inside andon the outside of the tube, for thepurposes of strengthening the tube to afford a stronger wall at the zoneof connection with other members. The provision of the reinforcement atseparated areas or zones of the tube is of particular value inconnection with members such as tubular front axles wherein the heavybosses or reinforcements of the tube wall are required at the springshackle posts and for the king pins. For this purpose, the roll forgingdies may be undercut at the desired areas so as to reproduce on the flatblank the necessary reinforcement at the desired locations prior toforming the blank into tubular form.

I claim:

1. The method of forming a tubular member Inthese instances, cergreasessired shape to said first portion and to remove the lateral marginalportions of the end portion to provide an end portion of less width thanthe original strip of metal with parallel edges and merging with thesaid first portion of the blank on a gradual taper, rolling the blankinto tubular form about an axis extending longitudinally of the blank,and welding the-lateral edges thereof to provide a tube having at oneend a reduced diameter end portion of greater wall thickness than theportion of the tube contiguous thereto, heating said reduced end portionand immediately after heating subjecting the said end portion tosuccessive combined upsetting and forging operations to impart a finaland different form thereto without reheating.

2. The method of forming atapered tubular member having and portions ofgreater thickness than the intermediate portion and tapering from oneendportion part way of the length of the tube toward the other, whichconsists of shearing from a band of uniform thickness and of metal, of awidth equal to the initial length of a desired blank, a plurality ofblanks, each of which is tapered from one of its ends to its other end,said blanks being out from the band with like ends of adjacent blanksbeing oppositely arranged with respect to each other, whereby they arein nested relation and waste material is eliminated in the cuttingoperation, roll-forging each blank to reduce the thickness thereof atthe portion between and spaced from the end portion and to increase thelength of the blank, trimmine the edges of the roll-forged blank aboutan axis extending longitudinally of the blank, to the desiredconfiguration, rolling the entire blank into tubular form and Weldingall the lateral edges thereof to form a tube tapering from adjacent oneend toward the other end and having its smaller diameter end portion ofgreater wall thickness than the tapered portion, heating said endportion and then subjecting the said smaller end portion to successivecombined upsetting and forging operations, without reheating, forimparting the final configuration required to the thickened wallportion,

3. The method of forming elongated tubes with thickened and flanged endportions, comprising roll-forging an elongated sheet metal blank ofapproximately uniform thickness throughout its area, but of lessthickness than desired for the end portion, to thin the same across itsentire width and while leaving an end portion unreduced in thickness,trimming both side edges of the forged blank, bringing the side edgestogether and welding them to form the tube, then heating thethick-walled end portion of the tube and CERTIFICATE OF CORRECTION.

Patent No. 2,196,L|.97.. April 9, 19140.

HOMER n. HIEHAN.

It is hereby certified that; error appears in the printed specificationof the above numbered patent requiring correction asfollows; Page )4,sec- 0nd column, lines 11.5 and 14.6, claim 2, strike out the words andcomma "about an'axis extending longitudinally of the blank," and insertthe same after "form" in line 148, same claim; and thatthe said LettersPatent should be read with'this correction therein that the same mayconform to the record or the case in the Patent Office.

' Signed and sealed this hen day. of June, A. D". 191m.

. Henry Ven Arsdale, Acting Commissioner of Patents.

